As disclosed in, for example Japanese examined patent publication No. Sho. 63-8824, in a conventional mail sorter, mail recovery boxes are arranged in a series along the lower region of a mail sorting line in which a number of conveyor baskets circulate. Each recovery box is associated with a sorting operator or a sorting receiver which selects the recovery box to receive the mail from the conveyor basket. The conveyor baskets circulate past every sorting receiver in the series. The respective mail pieces are released from the conveyor baskets and are recovered in the mail recovery boxes selected by the receiver. It is noted that the term “mail” in the present invention means a sheet-shaped piece of mail in which a flat object such as a magazine or the like was sealed.
Further, with the disclosed form of the mail recovery boxes, a simple one stage system is adopted along the mail sorting line taking the form of the mail recovery boxes into consideration so that a sorting operator can smoothly perform sorting recovery operation, maintenance operation and the like, and so that the mail released from the conveyor baskets in a state of circular movement can be reliably recovered into the mail recovery boxes through sufficient receiving spaces.
However, since such a conventional mail sorter adopts one-stage system as a form of mail recovery boxes, when a number of sorting receivers are required, mail recovery boxes are arranged around the substantially entire periphery of the mail sorting line or the mail sorting line itself is elongated.
When the former is used, an operation area for the operator must be ensured to some extent around the substantially entire periphery of the mail sorting line and there occurs a problem that the mail sorting line cannot be provided near a side wall of the building, that is a restriction on the design of the line. On the other hand, when the latter is used, the space for providing the mail sorting line becomes limited.
Alternatively, when the conventional mail sorting line comprising a number of circulating conveyor baskets, and mail recovery boxes arranged along the lower region of the conveyor baskets may be provided in upper and lower two stages, the space limitation in a viewpoint of floor space of the building due to the elongation of the line itself can be removed. However, since an operating position where the operator is liable to operate easily is occupied as an conveyor space for the conveyor baskets on the mail sorting line provided on the lower side, the setting height of the mail recovery box is restricted in its space and the workability is also remarkably limited.
Alternatively, when the above-mentioned problems are intended to be solved by layering only the mail recovery boxes in multi-stages along a mail sorting line, the mail sorting line on which a number of conveyor baskets are moved in circulation, is provided at a higher position of the building and the mail recovery boxes must be layered in multi-stages in the lower region. Accordingly, there were problems that a great drop is generated between the conveyor baskets and the mail recovery boxes on the lowest stage whereby mail may be damaged and the likelihood of a recovery error is also created. In addition to the operational problems, there was a problem that the maintenance operations for the circulating conveyor baskets could be impaired.